Quality of life and psychosocial outcomes among children with metabolically healthy and unhealthy obesity.

BACKGROUND: Obesity and obesity-related morbidities are associated with poor psychosocial adjustment and health-related quality of life (HRQoL). This study aims to examine HRQoL and psychosocial outcomes in children with metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO), and the effects of familial health on these outcomes. METHODS: Four hundred and six children with BMI for age ≥ 97th percentile were classified as having MHO and MUO based on the absence or presence of metabolic abnormalities. HRQoL and psychosocial outcomes were assessed using validated questionnaires such as PedsQL and DASS-21. RESULTS: There were no significant differences in HRQoL and psychosocial outcomes between children with MHO and children with MUO. Children with MUO and prior knowledge of existing metabolic conditions reported significantly lower total HRQoL (71.18 ± 17.42 vs. 75.34 ± 15.33), and higher depression (12.16 ± 11.80 vs. 8.95 ± 8.52) and stress (12.11 ± 8.21 vs. 10.04 ± 7.92) compared to children with MHO. Children with MUO who had fathers with metabolically unhealthy phenotype reported significantly lower total HRQoL (72.41 ± 15.67 vs. 76.82 ± 14.91) compared to children with MUO who had fathers with metabolically healthy phenotype. CONCLUSION: Prior knowledge of existing metabolic abnormalities was associated with poorer HRQoL and mental health in children with obesity. Paternal metabolic health status influenced HRQoL in children with MUO. IMPACT: First study that compared health-related quality of life (HRQoL) and psychosocial outcomes between children with metabolically healthy obesity (MHO) and children with metabolically unhealthy obesity (MUO). No significant differences in HRQoL and psychosocial outcomes between children with metabolically healthy obesity (MHO) and children with metabolically unhealthy obesity (MUO). Children with MUO who had prior knowledge of existing metabolic conditions reported lower HRQoL, higher depression and stress compared to children with MHO. Paternal metabolic health status was found to influence HRQoL in children with MUO. Mental health support intervention with paternal involvement should be provided for children with MUO.

The effects of glucagon-like peptide (GLP)-1 receptor agonists on weight and glycaemic control in Prader-Willi syndrome: A systematic review.

OBJECTIVE: The mainstay management of hyperphagia and obesity in Prader-Willi syndrome (PWS) relies on dietary restrictions, strict supervision and behavioural modifications, which can be stressful for the patient and caregiver. There is no established pharmacological strategy to manage this aspect of PWS. Theoretically, glucagon-like peptide-1 (GLP-1) receptor agonists (GLP1-RA) used in patients with obesity and type 2 diabetes mellitus (T2DM) may be efficacious in weight and glycaemic control of PWS patients. We conducted a systematic review of the literature to summarize the evidence on the use of GLP1-RA in PWS patients. DESIGN: Primary studies were searched in major databases using key concepts 'Prader-Willi syndrome' and 'GLP1 receptor agonist' and outcomes, 'weight control OR glycaemic control OR appetite regulation'. RESULTS: Ten studies included, summarizing GLP1-RA use in 23 PWS patients (age, 13-37 years), who had used either exenatide (n = 14) or liraglutide (n = 9) over a duration of 14 weeks to 4 years. Sixteen (70%) of these patients had T2DM. Ten patients experienced improvement in body mass index, ranging from 1.5 to 16.0 kg/m2 , while improvement in HbA1c was seen in 19 of 23 cases, ranging between 0.3% and 7.5%. All five studies reporting appetite or satiety showed improvement in satiety levels. There were no reported serious side effects. CONCLUSIONS: GLP1-RA appears safe in PWS patients and may have potential benefits for weight, glycaemic and appetite control. Nonetheless, we also highlight a significant gap in the literature on the lack of well-designed studies in this area, which limits the recommendation of GLP1-RA use in PWS patients at present.

Prevalence and predictors of metabolically healthy obesity in severely obese Asian children.

BACKGROUND: Obese individuals who have little or no metabolic syndrome components are proposed to be "metabolically healthy obese (MHO)". This study aim to evaluate the prevalence of MHO and examine the predictors associated with MHO in a multi-ethnic Asian cohort of severely obese children. METHODS: This study included a cross-sectional cohort of 406 Chinese, Malay and Indian children aged 5-20 years old with BMI for age ≥ 97th percentile. Metabolic syndrome (MS) and metabolic health (MH) definitions based on the presence or absence of metabolic abnormalities (High triglycerides, low HDL cholesterol, elevated blood pressure and high glucose) were used to define MHO in the cohort. RESULTS: The prevalence of MHO is 63.5% by MS definition and 22.4% by MH definition. Maternal healthy metabolic status (OR: 2.47), age (OR: 0.83, 0.80), paternal obesity (OR: 0.48, 0.53), Malay (OR: 1.97) and Indian ethnicity (OR: 6.38, 3.21) (compared to Chinese ethnicity) are independent predictors for MHO phenotype based on different MHO definitions. CONCLUSIONS: Adiposity measures are not associated with MHO phenotype, but instead younger age, maternal healthy metabolic status, absence of paternal obesity, Malay and Indian ethnicity are independent predictors for MHO phenotype in a multi-ethnic Asian cohort of severely obese children. IMPACT: The prevalence of metabolically healthy obese (MHO) in our multi-ethnic Asian cohort of severely obese children is 63.5% and 22.4%, respectively, based on different MHO definitions. Adiposity measures are not associated with the MHO phenotype. There are other factors that contribute to the metabolic phenotype in obese individuals. Younger age, maternal healthy metabolic status, absence of paternal obesity, Malay and Indian ethnicity are independent predictors for MHO phenotype. Parental influence is important in predicting metabolic health in obese individuals.

Self and parent-proxy rated health-related quality of life (HRQoL) in youth with obesity: are parents good surrogates?

PURPOSE: Consideration of health-related quality of life (HRQoL) and wellbeing outcomes is important to guide healthcare services for youth with obesity, yet youth perspectives may differ from their parents. This study compared youth and parental HRQoL reports and evaluated levels of concordance across HRQoL domains and as a function of youth age, youth gender and parent informant (mother and father). METHODS: 376 youths with obesity, recruited from community (N = 223) and hospital settings (N = 153), and their parents (N = 190 mothers; N = 91 fathers), completed the PedsQL. Parental and youth agreement across subgroup dyads (mother; father; child gender; child age) were evaluated using Wilcoxon signed-rank test, intra-correlations coefficients (ICCs) and Bland-Altman plots. RESULTS: Compared to norms, HRQoL levels (youth self-report and parental proxy reports) were lower in all domains. Both mother and fathers' HRQoL reports were significantly lower than youths, most notably in physical HRQoL. Youth-parent concordance ranged from poor to moderate (ICC = 0.230-0.618), with lowest agreement for Physical HRQOL. Mothers were better proxies with ICCs being significant in all domains. Youth-father ICCs were significant only for Social (ICC = 0.428) and School (ICC = 0.303) domains. Girl-mother agreement was significant across all domains, while girl-father agreement was significant only in the Social domain (ICC = 0.653). Both mothers and fathers were poor raters for boys, and younger youths (aged ≤ 12), with non-significant ICCs in most HRQoL domains. CONCLUSIONS: Parents are poor surrogates for youth HRQoL. Clinicians should be cognizant that parents are not necessarily accurate proxies for youths, and exercise caution when interpreting parent-proxy scores.

In-vitro function of upstream visfatin polymorphisms that are associated with adverse cardiometabolic parameters in obese children.

BACKGROUND: Visfatin is an adipokine associated with glucose and lipid metabolism. We previously reported two visfatin upstream single nucleotide polymorphisms (SNPs), c.-3187G > A (rs11977021) and c.-1537C > T (rs61330082), which were in perfect linkage disequilibrium, in a Singaporean cohort of severely obese children and are associated with visfatin level and adverse cardiometabolic parameters. We aim to functionally characterize the effect of c.-3187G > A and c.-1537C > T SNPs on basal transcriptional activity. METHODS: A 1.6 kb and 3.7 kb upstream promoter region of the visfatin gene was amplified by polymerase chain reaction and separately cloned into luciferase reporter vectors. Successful clones were transfected into human embryonic kidney (HEK293T) and human breast carcinoma (MCF7) cells and in-vitro dual-luciferase assay was performed. Electrophoretic mobility shift assay (EMSA) was also conducted to examine the binding affinity between transcription factors and visfatin promoter sequences. RESULTS: Variant promoter with only c.-1537C > T SNP did not show a change in transcriptional activity as compared to the wild type. However, variant promoter with both c.-3187G > A and c.-1537C > T SNPs showed a statistically significant increase of 1.41 fold (p < 0.01) in transcriptional activity. The longer 3.7kbp visfatin promoter sequence was also shown to have significantly higher transcriptional activity (p < 0.05) as compared to the shorter 1.6kbp visfatin promoter. Both c.-3187G > A and c.-1537C > T variants showed an increased binding with nuclear protein. DISCUSSION AND CONCLUSIONS: We have demonstrated for the first time that visfatin variant promoter with both c.-3187G > A and c.-1537C > T SNPs result in an increase in transcriptional activity. This supports our previous finding and postulation that these SNPs contribute to elevated visfatin levels which may mediate higher triglyceride levels, severe systolic blood pressure and severe hypertension in obese children. These SNPs may co-operatively affect enhancer or silencer function to regulate transcriptional activity. In conclusion, this study shows that upstream visfatin SNPs could potentially affect phenotypic outcome in obese children through alteration of circulating visfatin level.

Ovarian germinoma accelerating the presentation of diabetes mellitus.

A 12-year-old girl presented to the Children's Emergency Department with symptoms of diabetes mellitus. Glutamic acid decarboxylase autoantibodies and anti-Islet cell antibodies were absent. She was also found to have ovarian dysgerminoma with markedly elevated serum ß-human chorionic gonadotropin (ß-HCG). With treatment of her ovarian tumor and normalization of the serum ß-HCG her insulin therapy was quickly discontinued and metformin started. The ovarian dysgerminoma appeared to have accelerated the presentation of severe diabetes. We hypothesized that the elevated ß-HCG and possibly other placental hormones from the germ cell tumor caused her to develop insulin resistance and inadequate ß-cell insulin secretory response.

Familial male-limited precocious puberty in neurofibromatosis type I.

UNLABELLED: Precocious puberty in patients with neurofibromatosis type 1 (NF-1) is predominantly central in origin, with intracranial pathologies like optic glioma. We describe one patient with NF-1 who presented with precocious puberty with the eventual diagnosis of familial male-limited precocious puberty and share the potential pitfalls. He presented at 7 years of age with growth spurt and pubertal genitalia development with enlarged testicular volume of 7 mL, but LHRH stimulation test revealed blunted luteinizing hormone and follicle-stimulating hormone peak suggestive of a peripheral cause, contrary to the expectation due to the background of NF-1. Testosterone level was elevated with bone age advancement by 2 years. Genetic analysis revealed a previously reported heterozygous missense mutation of the luteinizing hormone/choriogonadotropin receptor gene Ala572Val. His father was also heterozygous for the same mutation but was apparently asymptomatic and not short. CONCLUSION: Our report illustrates two potential pitfalls in the clinical evaluation of patients with familial male-limited precocious puberty (FMPP). Firstly, patients with FMPP will have mild to moderately enlarged testes and should not be wrongly diagnosed as central precocious puberty without the gonadotropin-releasing hormone stimulation test. Secondly, family members with the same mutation may have different phenotypic severities, where some male carriers may have subtle features.

The role of glucagon-like peptide 1 receptor agonists for weight control in individuals with acquired hypothalamic obesity-A systematic review.

Hypothalamic obesity does not respond well to conventional interventions for obesity. GLP-1 receptor agonists have mechanisms independent of the hypothalamus which may be potentially beneficial for managing hypothalamic obesity. This systematic review summarizes the efficacy and safety of GLP-1 receptor agonists use in hypothalamic obesity. A PRISMA-compliant systematic review was performed. Data was extracted from included studies and analysed based on change in weight, body mass index, glycaemic control, satiety, and safety profile with GLP-1 receptor agonist use. Ten studies comprising 5 case reports, 4 case series and 1 randomized-controlled trial included 54 patients (24 males, 30 females) with mean age of 25.2 (range 13-71) years with hypothalamic obesity who had received GLP-1 receptor agonists (exenatide = 48, liraglutide = 5 and dulaglutide = 1) over a mean duration of treatment of 12 (range 3-51) months. Mean weight reduction of 7.4 (SD 7.92) kg was observed in patients in whom weight was reported, with 85.7% of patients experiencing weight loss. All patients on liraglutide had weight reduction post-therapy. The sole trial had reported a non-significant reduction in BMI post-exenatide. Glycaemic control had either improved/maintained in all patients in whom this was measured. The main side effects of GLP-1 receptor agonist in individuals with hypothalamic obesity were nausea and vomiting; there were no major safety concerns. Based on limited published experience, GLP-1RA may be effective and safe for weight control in hypothalamic obesity, with the added benefit of improved glycaemic control in those with concurrent diabetes mellitus.

Screening for obstructive sleep apnea (OSA) in children and adolescents with obesity: A scoping review of national and international pediatric obesity and pediatric OSA management guidelines.

Obstructive sleep apnea (OSA) is a prevalent complication that affects up to 60% of children and adolescents with obesity. It is associated with poorer cardiometabolic outcomes and neurocognitive deficits. Appropriate screening and intervention for OSA are crucial in the management of children with obesity. We performed a scoping review of international and national pediatric obesity (n = 30) and pediatric OSA (n = 10) management guidelines to evaluate the recommendations on OSA screening in pediatric obesity. Sixteen (53%) of the pediatric obesity guidelines had incorporated OSA screening to varying extents, with no consistent recommendations on when and how to screen for OSA, and subsequent management of OSA in children with obesity. We provide our recommendations that are based on the strength and certainty of evidence presented. These include a clinical-based screening for OSA in all children with body mass index (BMI) ≥ 85th percentile or those with rapid BMI gain (upward crossing of 2 BMI percentiles) and the use of overnight polysomnography to confirm the diagnosis of OSA in those with high clinical suspicion. We discuss further management of OSA unique to children with obesity. An appropriate screening strategy for OSA would facilitate timely intervention that has been shown to improve cardiometabolic and neurocognitive outcomes.

Physical Activity and Nutrition Interventions for Type 1 Diabetes: A Meta-analysis.

BACKGROUND AND OBJECTIVES: Current evidence is lacking on physical activity and nutrition-based interventions focusing on the management of type 1 diabetes mellitus (T1DM) and health-related quality of life among children. To assess the effects of physical activity interventions and nutrition-based interventions for children with T1DM. METHODS: Data sources include the Cochrane Central Register of Controlled Trials, Medline, clinicaltrials.gov, the World Health Organization International Clinical Trials Registry Platform, CINAHL through January 2022. Study selection includes randomized controlled trials of children aged 18 years and below with T1DM comparing either a physical activity intervention, a nutrition-based intervention, or hybrid physical activity and nutrition-based intervention with placebo or no-treatment control. Data were pooled using a random-effects model. Primary outcomes were hemoglobin A1c (HbA1c), and health-related quality of life. RESULTS: Eighteen trials were included. Physical activity compared with the no-treatment group showed a lack of effect on HbA1c (mean difference = -0.58, 95% confidence interval -1.20 to 0.05; P value = .07). Nutrition-based intervention compared with no-treatment control for HbA1c level revealed a lack of effect (mean difference = -0.61, 95% confidence interval -1.48 to 0.26; P value = .17). Limitations include paucity of studies and low quality of evidence caused by the risk of bias. CONCLUSIONS: Despite the lack of significant evidence, the generally favorable results highlight the potential of such interventions in enhancing glycemic control and health-related quality of life. Additionally, promising results from a single physical activity-nutrition-based hybrid intervention in terms of glycemic control indicate the plausible effectiveness of a mixed intervention.

Screening for metabolic complications of childhood and adolescent obesity: A scoping review of national and international guidelines.

The rise in prevalence of childhood obesity is paralleled by an increase in obesity-related metabolic complications, which add significantly to the population burden of cardiovascular morbidity in the long term. Early detection of obesity-related metabolic complications through appropriate screening strategies forms a crucial aspect of obesity management. We performed a scoping review of international and national guidelines on the management of pediatric obesity to evaluate the recommendations on screening for metabolic complications, namely, hypertension, diabetes, dyslipidemia, and non-alcoholic fatty liver disease. Thirty guidelines were included, 23 (76.7%) of which had some guidance on screening for metabolic complications. However, there were significant variations in the extent and details of recommendations for screening for these metabolic complications. There has been no consensus on the body mass index (BMI) thresholds, age of onset, frequency, and screening tests recommended for detecting hypertension, diabetes, dyslipidemia, and non-alcoholic fatty liver disease between guidelines. These variations did not appear to be polarized based on geographical location or population ethnicity. We provide our recommendations on metabolic screening based on the strength of evidence in the guidelines, also incorporating recommendations from key childhood hypertension, diabetes, and lipid guidelines. Appropriate implementation of screening strategies is crucial to improve detection of metabolic complications, to allow for earlier or more intensified interventions for affected children with obesity.

A novel de novo androgen receptor nonsense mutation in a sex-reversed 46,XY infant.

An infant with 46,XY karyotype, and unambiguous female phenotype was found to have testes in the inguinal regions. Capillary sequencing of the androgen receptor (AR) gene identified a hemizygous de novo mutation (NM_000044.6:c.1621G > T) in exon 2 resulting in a termination codon p.(Glu541*) at the DNA binding domain (DBD). This novel nonsense mutation adds to the compendium of AR mutations which result in complete androgen insensitivity syndrome (AIS).

Association of leukocyte telomere length with obesity-related traits in Asian children with early-onset obesity.

BACKGROUND: Leukocyte telomere length (LTL) is associated with obesity and obesity-related traits, and there are ethnic-specific determinants of LTL. OBJECTIVE: To evaluate LTL associations with obesity and metabolic parameters in Asian children with early-onset obesity. METHODS: Genomic DNA was extracted from peripheral blood leukocytes of a cohort of children with (N = 371) and without obesity (N = 23), and LTL was measured using quantitative PCR (qPCR). Blood plasma was used for metabolic phenotyping. Statistical analysis was performed using SPSS and STATA. RESULTS: Children with obesity had shorter LTL (coefficient = -0.683, PAdj = 1.24 × 10-3 ) as compared to children who were lean. LTL was found to be associated with waist circumference (coefficient = -0.326, PAdj = 0.044) and skin-fold measures (coefficient between 0.267 and 0.301, PAdj between 4.27 × 10-4 and 7.06 × 10-7 ) in children with obesity. However, no significant associations were observed between LTL and metabolic parameters, and between LTL and inflammatory cytokines. LTL also did not significantly mediate the risk of non-alcoholic fatty liver disease (NAFLD) in children with obesity. CONCLUSIONS: We showed for the first time that Asian children with severe obesity had shorter LTL, and the shortening of LTL was associated with other adiposity measures including waist circumference and skin-fold measurements.

A case of X-linked adrenal hypoplasia congenita, central precocious puberty and absence of the DAX-1 gene: implications for pubertal regulation.

BACKGROUND/AIMS: X-linked adrenal hypoplasia congenita (AHC) is typically associated with DAX-1 mutations and hypogonadotropic hypogonadism. However, atypical cases of X-linked AHC in association with central precocious puberty and even normal puberty have rarely been reported, although the mechanism of action remains unknown. CASE REPORT: This is a case report of a boy with X-linked AHC associated with Duchenne muscular dystrophy, whose clinical presentation led to analysis of the DAX-1, glycerol kinase (GK1) and dystrophin genes, which were amplified by polymerase chain reaction, with Southern blot analysis of the AHC locus. RESULTS: There was a non-contiguous deletion of the DAX-1 and GK1 genes, with deletion of the dystrophingene from exons 3 to 79. CONCLUSION: This is the first report of X-linked AHC, central precocious puberty in the absence of the DAX-1 gene. The fact that a 'loss of function' DAX-1 mutation can be associated with hypogonadotropic hypogonadism, precocious and normal puberty, suggests that DAX-1 is but one of several transcription factors which regulate puberty, and provides further evidence that other transcription factors may interact with DAX-1 and influence gonadal regulation in a complex, but hierarchical fashion.

Novel melanocortin 4 receptor gene mutations in severely obese children.

OBJECTIVE: Melanocortin 4 receptor (MC4R) deficiency is the commonest monogenic form of obesity. The significance of MC4R mutations in Asian obese populations has not been adequately examined. The objective of this study was to determine the role of MC4R mutations in severely obese Asian children. DESIGN: We screened 227 obese local children and adolescents for MC4R gene mutations by polymerase chain reaction and direct sequencing. RESULTS: We identified three mutations in three subjects: 4 bp deletion from nucleotides 631-634 (c.631-634delCTCT), Tyr157Ser (c.470 A > C) and 1 bp deletion at nucleotide 976 (c.976delT) (1.32% of study subjects). The latter two mutations are novel. The Tyr157Ser mutation was not found in 188 non-obese controls using restriction enzyme digest analysis. In vitro transient transfection studies supported the pathogenic role of both novel mutations Tyr157Ser and c.976delT, where the signalling activities of the mutant receptors were impaired. Heterozygous MC4R mutations were associated with early-onset severe obesity, and homozygosity of the MC4R mutation Tyr157Ser resulted in morbid obesity. CONCLUSION: MC4R mutations result in an autosomal codominant form of obesity with variable expressivity. MC4R deficiency is not as common among the obese children in this study compared to other populations. Family studies revealed that adults heterozygous for the mutations were less obese compared to the children. We hypothesize that this may be due to amelioration of phenotype severity with age, genetic anticipation or difference in exposure to modifying factors at critical stages of childhood such as the environment.

Association of raised liver transaminases with physical inactivity, increased waist-hip ratio, and other metabolic morbidities in severely obese children.

OBJECTIVE: To identify factors associated with raised alanine transaminase, aspartate transaminase, and gamma-glutaryl transferase in severely obese children PATIENTS AND METHODS: In all, 201 children with early-onset obesity and greater than 140% ideal weight for height were recruited. Anthropometric and body fat measurements, fasting blood tests, and oral glucose tolerance tests were performed. RESULTS: The mean and standard deviation (SD) for age was 11.1 (3.0) years, for weight for height 170.5% (22.7%), and for percentage body fat was 40.7% (5.2%). Elevated liver transaminases were present in 53 subjects (26.4%), who were therefore at risk for nonalcoholic fatty liver disease, and was associated with male sex (odds ratio [OR] 2.144, 95% confidence interval [CI] 1.033-4.448), Chinese ethnicity (OR 2.062, 95% CI 1.038-4.096), reduced physical activity (OR 2.389, 95% CI 1.163-4.909), insulin resistance (P < 0.05), elevated triglyceride levels (P = 0.029), and increased waist-hip ratio (P = 0.005). Stepwise logistic regression analysis of the main factors as covariates revealed Chinese ethnicity, waist-hip ratio, reduced physical activity, and homeostasis model assessment index were significant predictors. Alanine transaminase/aspartate transaminase were not well correlated with percentage body fat and weight for height. Subjects with type 2 diabetes mellitus and impaired glucose tolerance were more likely to have raised hepatic transaminases (OR 6.176, 95% CI 1.326-28.754). The severity of metabolic syndrome correlated with increasing aspartate transaminase, alanine transaminase, and gamma-glutaryl transferase (P < 0.01). CONCLUSIONS: Insulin resistance, truncal adiposity, and physical inactivity are major determinants potentially modifiable to reduce risk of nonalcoholic fatty liver disease. Increasing physical activity levels were associated with decreasing insulin resistance and transaminases, despite lack of correlation with waist-hip ratio, which supports the direct benefit of regular physical activity in preventing nonalcoholic fatty liver disease.

3rd College of paediatrics and child health lecture--the past, the present and the shape of things to come...

The growth trends of Singapore children spanning 5 decades are reviewed, based on 8 anthropometric studies from 1957 till 2002. The heights of pre-school children and school age children appear to have optimised according to their genetic potential, but the weights and body mass indices of children still appear to be increasing from 6 to 18 years for both sexes, probably as a consequence of increasing affluence. This trend is reflected in the increasing obesity prevalence in school children over the past 30 years, and the concomitant increased morbidity associated with the metabolic syndrome, necessitates further research into the causes of obesity. Barker's hypothesis first suggested that changes in the intra-uterine environment can cause fetal adaptations which persist into adulthood, and are responsible for many chronic diseases of adult life. More recently, intense research in the field of epigenetics suggests that the environment can also influence the phenotype through gene expression, through modification of DNA methylation and histones which, in turn, influences gene expression. The challenge for the future is to determine if there are clear epigenetic changes, which are responsible for the increased prevalence of childhood and adolescent obesity, and whether these changes are transmitted through generations. Unravelling these epigenetic mechanisms may be the key to the prevention of obesity and the metabolic syndrome.

A diagnostic curiosity of isolated androstenedione elevation due to autoantibodies against horseradish peroxidase label of the immunoassay.

Two sisters with hirsutism presented with mild hirsutism and isolated, grossly elevated (>34.9nmol/L) serum concentrations of androstenedione measured by competitive, homogeneous immunoassay. The clinically discordant laboratory results prompted us to look for assay interference. In this immunoassay, horseradish peroxidase (HRP)-conjugated androstenedione competes with endogenous androstenedione for binding with the solid-phase polyclonal rabbit IgG antibodies. After a wash step, the amount of signal generated by the bound HRP conjugate is inversely proportional to the androstenedione concentration. Alternative analysis by tandem mass spectrometry (a good first line option for troubleshooting) and repeating the competitive immunoassay after polyethylene glycol treatment returned androstenedione concentrations within reference limits. These findings suggested that the original result was spuriously elevated due to assay interference. Additionally, the patient samples were pre-incubated with heterophile blocking reagents, normal rabbit IgG antibodies and HRP-conjugated normal goat IgG antibodies, followed by repeat measurement using the immunoassay. Only samples pre-incubated with HRP-conjugate returned significantly lower androstenedione (9.5 and 12.5nmol/L, respectively), implying neutralisation of the interfering antibodies. Androstenedione remained grossly elevated in the other experiments. This deductive exercise showed that the interference is due to autoantibodies against the HRP label used in the immunoassay. Another immunoassay using HRP label (5α-dihydrotestosterone) also produced gross elevation that was normal by tandem mass spectrometry analysis. Assay interferences, though not uncommon, are frequently overlooked. Laboratory results discordant with clinical features should prompt consideration of assay interference to avoid unnecessary investigations and treatment. This is the first report of autoantibodies against the HRP label used in immunoassay.